1. Field of the Invention
The invention relates to a door lock wherein the rotary latch receives in its one rotary end position, i.e., its locking position, a locking member which drops into a main catch and locks the retainer against its spring-load. In order to transfer the rotary latch into its open position, the retainer is released. For releasing the retainer, a motor-driven working member is used. The motor is activated, in the case of authorized access of the user, when, for example, an actuator belonging to the door lock is directly or indirectly actuated.
2. Discussion of Related Art
In a known door lock of this kind (DE 197 25 416 C1) a force storage device loads the arm of a storing member which is supported on the motor-driven working member and thus defines the charged state of the force storage device. This storing member has a shoulder which, for the purpose of lifting the retainer, impacts against a counter shoulder on an arm of the retainer in order to lift, in the normal situation as well as in a special situation, for example, in a crash, the retainer from its locking position in the rotary latch by releasing the force storage device. In this connection, the storing member has a control surface on which the motor-driven working member is supported. The retainer has a long arm in whose end area a counter control surface is provided against which the working member moves in a second phase, which is time-delayed relative to the first motor drive phase, during lifting of the retainer out of the rotary latch.
This door lock has proven to be successful because in the special situation the energy amounts of the motor applied successively in the first and second motor drive phases are transferred simultaneously by the shoulder onto the counter shoulder; however, manufacturing-technological and operating-related disadvantages result. The arm provided on the retainer must have a great length because of the counter control surface so that the center of gravity of the retainer is spaced at a great distance relative to its fulcrum. This requires complex manufacturing methods. Safety regulations require that the door lock in a crash situation must withstand high inertia forces, for example, inertia forces which reach 30 times the acceleration due to gravity. In order to avoid an automatic opening of the door lock, the restoring springs of such a known lock would have to be very strong. This had the result that the required actuating forces for lifting the retainer out of the rotary latch were high. The opening action of the known door lock was therefore stiff.
The invention has the object to develop a door lock of the aforementioned kind which avoids the aforementioned disadvantages. This is achieved according to the invention in that not only the control surface but also the counter control surface is provided on the storing member, in that in the special situation the required additional motor force for lifting the retainer is indirectly transmitted via the storing member onto the retainer, and in that, by doing so, the energy amounts successively applied in the two motor drive phases are then transmitted simultaneously from the shoulder of the storing member onto the counter shoulder of the retainer.
According to the invention, the control surface as well as the counter control surface are provided on the storing lever. Accordingly, the arm on the retainer, which is to receive during release of the force storage device the released lifting force for the retainer, can be very short. Thus, the center of gravity of the retainer is very close to its fulcrum. The motor-generated lifting energy required in the special situation for lifting the retainer is also transferred from the working member onto the storing member. The energy amounts which are successively exerted in the two motor drive phases are transferred after a crash via the same locations, i.e., always from the shoulder of the storing member onto the counter shoulder of the retainer. These locations can also be very close to the fulcrum of the retainer. The restoring spring acting onto the retainer can be of a weaker design which makes possible an easy opening action.